What is the general formula of halide salts of alkali metals if $M$ is a metal atom and $X$ is a halogen atom?

Sodium reacts more vigorously with water than lithium because...

Which of the following statements is not true for most of the alkali metals?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ Lithium salts are hydrated.
Reason $(R):$ Lithium has higher polarising power than other alkali metal group members.
In the light of the above statements,choose the most appropriate answer from the options given below:

Sodium is heated in air at $300^{\circ} C$ to form $X$. $X$ absorbs $CO_2$ and forms $Na_2CO_3$ and $Y$. Which of the following is $Y$?

Which of the following reactions does not liberate a gaseous product?